1. Field of the Invention
This application relates to compressed gas powered guns. More specifically, the invention relates to training guns duplicating various characteristics of guns firing gunpowder propelled projectiles.
2. Description of the Related Art
Guns firing projectiles propelled by compressed air or gas are commonly used for recreational target shooting or as training devices for teaching the skills necessary to properly shoot guns firing gunpowder propelled projectiles. Ammunition for air guns is significantly less expensive than gunpowder propelled ammunition. A typical gas powered projectile has significantly lower velocity and energy than a gunpowder propelled projectile, making it much easier to locate a safe place to shoot an air gun, and much less expensive to construct a suitable backstop. Additionally, the low velocity and energy of air powered projectiles makes air guns significantly less useful as weapons than guns firing gunpowder propelled projectiles. Lack of usefulness as a weapon is an important factor in making air guns available in regions where national or local governments regulate firing gunpowder propelled projectiles (firearms).
To be an effective training tool, an air gun must duplicate the characteristics of a firearm as closely as possible. These characteristics include size, weight, grip configuration, trigger reach, type of sights, level of accuracy, method of reloading, method of operation, location of controls, operation of controls, weight of trigger pull, length of trigger pull, and recoil. The usefulness of a gas powered gun as a training tool is limited to the extent that any of the above listed characteristics cannot be accurately duplicated.
Presently available air guns increasingly tend to have an exterior configuration resembling that of a gun firing a powder propelled projectile. Presently available air guns may be used in a semi-automatic (one shot per pull of the trigger) or very rarely full automatic (more than one shot per pull of the trigger) mode of fire, although the cyclic rate of full automatic fire typically does not duplicate the cyclic rate of a full automatic firearm firing a projectile powered by gunpowder. The vast majority of presently available airguns which are advertised as being semiautomatic are actually nothing more than double-action revolver mechanisms disguised within an outer housing that simply looks like a semiautomatic gun. However, because they are true double-action mechanisms, the weight of trigger pull is much heavier than the weight of trigger pull of the present invention, which has a true single-action trigger. Presently available air guns have also been designed to simulate the trigger pull and reloading of guns firing gunpowder propelled projectiles.
Presently available air guns do not duplicate the recoil of a gun firing a powder propelled projectile. The inability to get a trainee accustomed to the recoil generated by conventional firearms is one of the greatest disadvantages in the use of air guns as training tools. Additionally, although presently available air guns can be made extremely accurate, variations in gas pressure can cause differences in shot placement from shot to shot, or from the beginning of a gas cartridge to the end. Further, duplication of the cyclic rate of a conventional firearm within an air gun would enable a trainee to learn how to properly depress the trigger to fire short bursts of approximately three shots in full automatic mode of fire using an air gun. Because recoil is significantly more difficult to control during full automatic fire than during semi-automatic fire, an air gun simulating both recoil and the cyclic rate of a conventional firearm would be particularly useful as a training tool.
Accordingly, there is a need for an air powered gun duplicating the recoil of a conventional firearm. Additionally, there is a need for an air powered gun maintaining a consistent compressed gas pressure behind the projectile from shot to shot, thereby maintaining a constant velocity, energy, and point of impact for each projectile. Further, there is a need for an air gun duplicating the full automatic cyclic rate of a conventional full automatic firearm. There is also a need to combine these characteristics into an air gun that is not particularly useful as a weapon, thereby facilitating safe use by inexperienced trainees, making training facilities easier and more economical to construct, lowering the cost of ammunition and training, reducing noise levels, and broadening the legality of ownership.
The preferred embodiment of the invention is an air or gas powered gun providing a recoil similar to that of a gun firing a powder propelled projectile. The compressed gas powered gun includes an improved magazine and magazine indexing system, contributing to the accuracy of the gun. The compressed gas powered gun preferably also duplicates many other features of a conventional firearm, for example, the sights, the positioning of the controls, and method of operation. One preferred embodiment simulates the characteristics of an AR-15 or M-16 rifle, although the invention can easily be applied to simulate the characteristics of other conventional firearms.
The operation of a compressed gas powered gun of the present invention is controlled by the combination of a trigger assembly, bolt, buffer assembly and valve. Preferred embodiments will be capable of semi-automatic fire, full automatic fire at a low cyclic rate, and full automatic fire at a high cyclic rate. One of the two full automatic cyclic rates preferably approximately duplicates the cyclic rate of a conventional automatic rifle, for example, an M-16 rifle.
The trigger assembly includes a trigger having a finger-engaging portion and a selector-engaging portion, a selector switch, a trigger bar, a sear trip, and a sear. The selector switch will preferably by cylindrical, having three bearing surfaces corresponding to safe, semi-automatic fire, and full automatic fire at a low cyclic rate, and a channel corresponding to full automatic fire at a high cyclic rate. These surfaces and channel of the selector bear against the selector engaging portion of the trigger, permitting little or no trigger movements if safe is selected, and increasing trigger movement for semi-automatic fire, low cyclic rate full automatic fire, and high cyclic rate full automatic fire, respectively. The sear is mounted on a sliding pivot, and is spring-biased towards a rearward position. The sear has a forward end for engaging the sear trip, and a rear end for engaging the bolt. The bolt preferably contains a floating mass, and reciprocates between a forward position and a rearward position. Although the bolt is spring-biased towards its forward position, the bolt will typically be held in its rearward position by the sear except during firing.
The valve assembly includes a reciprocating housing containing a stationary forward valve poppet, a sliding rear valve poppet, and a spring between the front and rear valve poppets. The spring pushes the rear valve poppet rearward, causing the rear poppet to bear against the housing, thereby closing the rear valve and pushing the housing rearward. Pushing the housing rearward causes the housing to bear against the front valve poppet, thereby closing the front valve.
Before the trigger is pulled, the trigger is in its forwardmost position, the bolt is held to the rear by its engagement with the sear, and the sear, although spring-biased rearward, is pushed towards its forwardmost position by the bolt. Pulling the trigger causes the trigger bar to move rearward, pivoting the sear trip upward. The upward movement of the sear trip pushes upward on the forward end of the sear, causing the rearward end of the sear to move down. The bolt is then free to travel forward, where the bolt strikes the rear valve, thereby moving the rear valve relative to the housing and opening the rear valve. Air pressure between the O-ring on the bolt face and the O-ring on the rear of the valve housing causes the housing to move forward, thereby opening the forward valve. Opening the forward valve dispenses pressurized gas to a position directly behind the projectile, causing the projectile to exit the barrel. Opening the rear valve supplies air pressure to the bolt face, thereby causing the bolt to return to its rearward position. If semi-automatic fire is selected, the limited movement of the sear trip, combined with the rearward spring-bias on the sear, causes the sear to move backwards on its pivot to a position where the sear trip can no longer apply upward pressure to the forward portion of the sear. The rear portion of the sear therefore pivots upward. The bolt will be propelled rearward to a point slightly behind the position wherein it engages the sear. As the bolt returns forward, the sear, which is no longer held in place by the sear trip, will engage the bolt, preventing further forward movement. From this position of the components, the trigger must be released before it can be pulled to fire another shot.
If full automatic fire at a slow cyclic rate is selected, the trigger may be pulled slightly farther to the rear before it engages the selector, thereby causing the sear trip to pivot slightly higher. Whereas the upper bearing surface of the sear trip pushes the sear up to initially release the bolt, here, the lower end bearing surface of the sear trip pushes the sear up sufficiently so that, when the bolt catches the sear, there is only about {fraction (1/32)}nd inch of engagement between the sear and bolt. The floating mass bolt is thereby momentarily held in its rearward position by the sear, which cams forward off the sear trip as the forward motion of the bolt pushes the sear from its rearward position to its forward position.
If full automatic fire at a high cyclic rate is selected, the trigger is allowed to travel to its maximum rearward position. The sear trip is thereby pivoted upward to its maximum extent, causing the lower end bearing surface of the sear trip to push the sear completely out of the way of the bolt. Therefore, as soon as the spring behind the bolt driver overcomes the rearward momentum of the bolt, the bolt will simply return forward and again actuate the valve.
A compressed gas powered gun of the present invention preferably includes a magazine and magazine indexing assembly configured to facilitate precise alignment of the firing chambers with the barrel. A preferred embodiment of the magazine is a cylinder. The term xe2x80x9ccylinderxe2x80x9d as used herein does not necessarily mean a perfect geometrical cylinder, but is used to denote a generally cylindrical magazine wherein a plurality of firing chambers are located around its circumference, as known to those skilled in the art of revolvers. A preferred cylinder will have six chambers, although this number may vary. The exterior surface of the cylinder will preferably include a plurality of flutes, with the flutes located between the chambers, and with an equal number of chambers and flutes. One preferred embodiment of the cylinder aligns the chamber with the barrel in the three o""clock position when viewed from the rear or the nine o""clock position when viewed from the front. A spring-biased bearing preferably engages the flutes, thereby precisely aligning the cylinder with the barrel. A preferred bearing will have a larger radius than the radius of the flutes, thereby maximizing the precision with which the chamber and barrel may be aligned. This arrangement permits the barrel and chamber to be aligned with such precision that a forcing cone is not needed at the breach of the barrel.
Indexing of the cylinder is controlled by the forward and backward movements of the bolt. A spring-biased pawl mounted on a pawl carrier is located directly behind the cylinder. The pawl carrier reciprocates between a left most position and a right most position, with the left most position corresponding to the engagement of the pawl with one chamber of the cylinder, and the right most position corresponding to engagement of the pawl with another chamber of the cylinder. An operating rod extends forward from the bolt, overlapping the pawl carrier. The bottom surface of the operating rod includes an angled slot, dimensioned and configured to guide an upwardly projecting pin on the pawl carrier. With the bolt in its rear most position, the pawl carrier pin is located in the forwardmost portion of the operating rod""s angled slot. The pawl carrier and pawl are therefore in their right side position. The pawl is spring-biased forward to engage the chamber in the one o""clock position when viewed from the rear, or the eleven o""clock position when viewed from the front. As the operating rod moves forward due to forward travel of the bolt, the pawl carrier is moved from its right side position to its left side position. The left side of the pawl includes a ramped surface which permits the pawl to be pushed rearward by the cylinder wall, against the bias of the spring, allowing the pawl to move from the top right side chamber to the top left side chamber. When the bolt returns to its rearward position, the pawl and pawl carrier are moved from their left side position to their right side position. The right side of the pawl is parallel to the inside of the cylinder wall, so that movement of the pawl from left to right will cause the cylinder to index in a clockwise direction when viewed from the rear, or a counterclockwise direction when viewed from the front. The bearing will be biased out of the current flute, and will bear against the next flute at the completion of indexing, thereby properly aligning the next firing chamber with the barrel.
Another preferred embodiment includes a tubular magazine in addition to the cylinder. The tubular magazine is aligned with one chamber of the cylinder whenever another chamber of the cylinder is aligned with the barrel. The tubular magazine includes a spring-biases follower for pushing projectiles rearward into the cylinder. Whenever the cylinder is indexed, another projectile will thereby be pushed into an empty chamber of the cylinder as that chamber is aligned with the tubular magazine.
If no tubular magazine is present, or if use of only the cylinder is desired, a preferred method of reloading the compressed gas powered gun is to remove the cylinder, place a single pellet into each chamber, and then replace the cylinder. If the tubular magazine is used, a preferred method of loading the compressed gas powered gun includes retracting the follower using a finger tab secured to the follower and extending outside the gun, opening a loading gate, and pouring projectiles into the tubular magazine. Preferred projectiles for use of a tubular magazine include spherical pellets. Preferred projectiles for use with the cylinder alone include spherical pellets or conventional air gun pellets.
A compressed gas powered gun of the present invention uses a recoiled buffer system for biasing the bolt forward, and for providing a recoil for the shooter. A preferred buffer system includes a floating mass bolt driver, and an air resistance bolt driver, with a spring disposed therebetween. This assembly is located in a tube within the air gun""s shoulder stock, which is preferably a cylindrical tube. The buffer assembly may be oriented so that either the air resistance bolt driver or the floating mass bolt driver is positioned directly behind the bolt, with the other bolt driver placed at the rear of the stock. The forward bolt driver will thereby abut the rear of the bolt, pushing the bolt forward.
If the air resistance bolt driver is positioned directly behind the bolt, light recoil results. The air resistance bolt driver has less mass than the floating mass bolt driver, resulting in less mass reciprocating back and forth. Additionally, the air resistance bolt driver will trap air behind it as it reciprocates, thereby slowing travel of the reciprocating mass. Conversely, positioning the floating mass bolt driver behind the bolt results in heavier recoil, due to the increased reciprocating mass and the lack of the ability of the floating mass bolt driver to trap air. The shooter may therefore select the desired level of recoil to correspond with the recoil of the conventional firearm the shooter wishes to simulate.
It is therefore an aspect of the present invention to provide a compressed gas powered gun simulating the recoil of a conventional firearm.
It is another aspect of the present invention to provide a compressed gas powered gun wherein the level of recoil provided to the shooter may be selected by the shooter.
It is further aspect of the present invention to provide a compressed gas powered gun capable of simulating the operation of a conventional firearm.
It is another aspect of the present invention to provide a compressed gas powered gun capable of both semi-automatic and full automatic operation.
It is a further aspect of the present invention to provide a compressed gas powered gun wherein different cyclic rates of full automatic fire may be utilized.
It is another aspect of the present invention to provide a compressed gas powered gun utilizing a magazine and magazine indexing system providing precise alignment of the firing chambers with the barrel.
It is a further aspect of the present invention to provide a compressed gas powered gun capable of utilizing multiple types of projectiles.
It is another aspect of the present invention to provide a compressed gas powered gun for providing training that accurately simulates shooting a conventional firearm.
It is a further aspect of the present invention to provide a compressed gas powered gun that may be legally owned and utilized in locations where conventional firearms are heavily restricted.
Theses and other aspects of the present invention will become apparent through the following description and drawings.